There was no concept of name/address space or device virtualization in the Lisp Machine operating systems. I don't know the instruction set, but I have never se

There was no concept of name/address space or device virtualization in the Lisp Machine operating systems. I don't know the instruction set, but I have never seen references to privileged instructions or protection rings. Not that that would be an impediment - you would really want to do virtualization at the software level in a Lisp OS anyway.